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Big Gem Iron Earthcache EarthCache

Hidden : 09/19/2010
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Geocache Description:

This earthcache is located in lovely Shenandoah, VA.

Iron Ores are rocks and minerals from which metallic iron can be economically extracted. The ores are usually rich in iron oxides and vary in color from dark grey, bright yellow, deep purple, to rusty red. The iron itself is usually found in the form of magnetite (Fe3O4), hematite (Fe2O3), goethite (FeO(OH)), limonite (FeO(OH).n(H2O)) or siderite (FeCO3). Hematite is also known as "natural ore". The name refers to the early years of mining, when certain hematite ores contained 66% iron and could be fed directly into iron making blast furnaces. Iron ore is the raw material used to make pig iron, which is one of the main raw materials to make steel. 98% of the mined iron ore is used to make steel.[1] Indeed, it has been argued that iron ore is "more integral to the global economy than any other commodity, except perhaps oil.”[2]

There are three different ways to identify sources of iron. Banded iron formations (BIF) are metamorphosed sedimentary rocks composed predominantly of thinly bedded iron minerals and silica (as quartz). Magmatic magnetite ore deposits, Occasionally granite and ultrapotassic igneous rocks, segregate magnetite crystals and form masses of magnetite suitable for economic concentration. A few iron ore deposits are formed from volcanic flows containing significant accumulations of magnetite phenocrysts. Hematite iron is typically rarer than magnetite bearing BIF or other rocks which form its main source or protolith rock, but it is considerably cheaper to process as it generally does not require beneficiation due to its higher iron content.

The Big Gem site was once the location of one of the most prominent iron production facilities in the south. Locals called the large furnace “Big Gem” because of the brilliant glow that radiated out of the ravine where the foundry and iron facility was located. With the exception of its brief use as a municipal landfill in the 1950’s, the Big Gem site remained idle from the 1890’s to 1998. Graduate students at James Madison University identified EPA’s Brownfields Pilot program as a potential fit for Shenandoah, leading to an EPA Assessment Pilot Award. More information can be found at Big Gem Park

The iron industry played a vital role in the industrialization of the United States and in the development of the U.S.economy and society. Much of the early history of the iron industry took place in Virginia. The remains of 11 iron furnaces and nearby mines in the George Washington and Jefferson National Forests in Virginia and West Virginia are silent reminders of a time when iron mines and furnaces operated along a belt that extended through the Appalachian Mountains from New York State to Alabama.

Why was iron found and exploited along this belt?

Iron mines and furnaces were operated in the long, northeast-trending belt of the Appalachians because two key ingredients of the iron industry iron ore and limestone (to remove impurities and promote fusing of the metal) are found here. To understand how iron and limestone formed in this long belt, envision the landscape as it appeared between 200 million and 540 million years ago. During that time, much of what is now the United States was covered by a vast, shallow sea. Shells and hard parts of ancient marine animals and plants fell to the bottom of this sea and accumulated to form deposits that later became limestone (calcium carbonate).

Taken from: Geologic Wonders of the George Washington and Jefferson National Forests No. 3 in a Series U.S. Department of Interior
U.S. Geological Survey in cooperation with U.S. Department of Agriculture Forest Service, Southern Region

When you visit Big Gem Park you will no longer see any exploits of the furnace, but rather an enjoyable recreational area with a pond for fishing and other activities. A fishing license is necessary.

To log this cache

1.take a picture of you or your gps and the pond in the background.

2. There are three ways iron ore deposits are identified. Looking at the surroundings and in particular the rocks across the pond, how do you think iron ore is presented in this area? Banded Iron Deposits, Magmatic Magnetite Ore Deposits, or Hematite Ore. You may need to do a little research to figure out the answer.

3.Why do you think the color of the water is as such?

4. From the coordinates, looking across the pond (facing N NE) you will notice the area lined with boulders. You will also notice some different colored bands in those boulders. What color are those bands and estimate the range of thickness in height of the band?

Email me the answers to these questions. PLEASE DO NOT POST ANSWERS in your log:

Additional Hints (No hints available.)